# Block universe theory [closed]

How to make sense of change in static block universe if every event already exist in block? if you say it's an illusion created by brain even that requires forward evolution of patterns of information in our brains,so what constitutes this change? If everything is just what it is in block and past, present and future exist simultaneously then how is there any change at all?

• things at time t1 don't have to be the same as at time t2 – user253751 Nov 12 '20 at 16:36
• every moment is being experienced for eternity – Wolphram jonny Nov 12 '20 at 16:40
• I am aware that different time slices have different events but inorder for us to perceive that difference some process should take place like conciousness jumping from one slice to another but how could that be ? If nothing changes ? – user279608 Nov 12 '20 at 16:57
• you should give a link for a "static" block universe, wikipedia has only a "growing block universe."en.wikipedia.org/wiki/Growing_block_universe. – anna v Nov 12 '20 at 18:01
• en.wikipedia.org/wiki/…. There you go . – user279608 Nov 12 '20 at 18:46

Look at a painting. The left is different from the right, the top is different from the bottom, and yet (if the painting is of something coherent) every little bit of the image is related in some way to the little bits on either side of it.

Look at a movie. The beginning is different from the end, but (almost) every frame is related to the frames before and after it, there's just a little bit of motion and change from one to the next. You can watch the movie from beginning to end, but you can also pop it out of the player, carry it around, put it in, rewind it, watch it later. The movie as a whole isn't changing, just the picture we see as we "move along its time axis".

Now look at the universe. Arguably it's just like the movie, except:

1. It's four-dimensional (at least).
2. There is, so far as we know, no director and no jump-cuts except for maybe the big bang. Every moment in time is related to the ones before and after it by what we call the "laws of physics".
3. We're stuck inside it, watching from the inside. Our act of perception is just another event occurring inside the universe, governed by its laws, which control how information reaches us along the time axis. My perception of "now" is mostly made up of things that happened near me in the recent past, and not of things that happen in the future, because that's how the universe works.

All of this is compatible with the idea that the universe is a "thing" which, if viewed from the outside, could be seen to contain all of time "all at once", just the way a DVD on the shelf contains the beginning and the end of the movie. But unless we can somehow attain an "outside" viewpoint, or interact with something that has it, it's purely a metaphysical question, not a physical one.

• I'm aware of everything you said but that's not my question . your movie analogy is perfect but how does this process of changing from one to another frame occur ? In short what's playing the block universe movie in forward direction ? Sean Caroll says it's the increase in entropy that creates arrow of time but how can one perceive this arrow at all ? – user279608 Nov 12 '20 at 17:03
• @BabyAssassin there is no playback process, just the fact that your consciousness at any moment incorporates information from its own past and not its future. – hobbs Nov 12 '20 at 17:21
• You say it incorporates information and the very act of incorporating information is an active process that requires change and there's also an updation of memory moment to moment how can that happen ? If nothing is changing. – user279608 Nov 12 '20 at 17:32
• @BabyAssassin forget the "nothing changes" nonsense. You accepted the existence of a time axis and of rules that relate the state at one time to the state at another time. That is change. If you accept that a moving object is at a different location depending on when you look at it, why apply a different set of rules to yourself? – hobbs Nov 12 '20 at 17:36
• Dear Hobbs thank you for being patient with me . consider the move analogy . The whole block universe can be treated as a movie upto to this point it's perfectly well . But then if you say "change in our perception " is due to changing move frames then you are describing " flow of time " which is not present in block universe . Or if you say our conciousness hops from one time slice to another time slice then that is also problematic because it implies both arrow of time and motion of something. – user279608 Nov 12 '20 at 18:22

You are thinking of change in far too restrictive of a sense. Consider a static cone. Even though the cone is static we can perfectly validly say that the radius of the cone cross section changes from apex to base. The radius is small near the apex and it gets large near the base. This would be described by $$\frac{d}{dx}r=k$$.

Mathematically, there is no difference between this and $$\frac{d}{dt}r=k$$. In this case, the latter could describe a circle whose radius is changing over time. Mathematically a dynamic circle which changes radius over time is the same as a static cone which changes radius from base to apex. The block universe simply takes that mathematical fact at face value.

The patterns of activity in our brains are similar to the cone’s radius. Just as the radius of the cone is a property of the cone which varies from base to apex, so the brain activity (voltage) is a property of the 4 dimensional object which varies over all 4 dimensions. There is nothing at all inconsistent with the block universe and the fact that this pattern changes in all four dimensions.

The two views are completely equivalent and you can equally describe the human mental state analogously to a dynamic circle or a static cone.

• I understand that in block universe each time slice is different than another and that constitutes a kind of "change" very similar to your cone analogy . The cone is a static object and the radius is different at each slice that's perfectly fine . But for us to perceive change as we do either of following things need to occur 1) there should be a flow of time . In that case we move through time slices hence we perceive change . 2) time doesn't flow but consciousness itself hops from one slice to another in that case we perceive change . Please tell me where i am going wrong . – user279608 Nov 12 '20 at 18:37
• Would you agree with this statement "The movie as a whole isn't changing, just the picture we see as we move along its time axis " ? If moving along time axis is possible in block theory then it's fairly straightforward to see how change occurs but I'm not sure about it . – user279608 Nov 12 '20 at 19:37
• @BabyAssassin It is not true that either 1) or 2) must be true for us to experience time as we do. In particular, 2) is not necessary. Our perception is simply a voltage pattern in our brain, and this is described in the second to last paragraph. There is no need for something additional called consciousness to be hopping along the voltage pattern. Consciousness is the voltage pattern in the block universe. – Dale Nov 12 '20 at 19:40

This is not an answer, but questions perhaps you might find related to your issue. The question you asks does not belong to physics, but to philosophy. Physics has nothing to say about the subjective experience (qualia) because it has no effect on the behavior of matter. Some, including Daniel Dennett even claim that qualia is an illusion and actually does not exist. Imagine a different scenario. You have a computer simulation in which the agents inside the program are conscious as we are. Are they only conscious when you run the program? What if you run the program backwards, or run it in individual steps, so it stops for a given time before running the next step. Will these beings experience qualia when the software is run that way? Or if you make a lookup table and the software is run by only reading from the lookup table. Or if the software is run by hand and paper (the famous "Chinese room")? Or not run at all?

As user253751 says in his comment, different points of the block can have different time values. So you need a direction for time and some kind of wave of time, that progresses in that direction. Basically the fully determined block universe is being read by the passing time, and we feel this as change.

• Yes true but how do we perceive that difference ? What moves from one time slice to another time slice ? How can something move when by definition nothing changes in block universe ? – user279608 Nov 12 '20 at 16:59
• If our awarness (whatever it is) is spread out over a small amount of time we could perceive change. Or another way to see it would be that the slice of the block universe is of non zero thickness – Marin Girard Nov 12 '20 at 17:03
• Yes but the very act of awareness or being concious is a process that occurs due to forward evolution of patterns of information in our brain but how could that be possible if nothing is supposed to change ? – user279608 Nov 12 '20 at 17:06